Modern ducted fan gas turbine engines are conventionally provided with a front fan which comprises a plurality of radially extending aerofoil blades mounted on a common hub or disc. Each fan blade is provided at its radially inner end with a root, often of dovetail cross-sectional form, which locates axially in a correspondingly shaped retention groove formed in the fan disc.
The fan blades are relatively large in order to ensure that they satisfy the air flow requirements of the engine. They also must be sufficiently robust to withstand the impact of airborne foreign objects which may be drawn into the engine. This all results in fan blades which are heavy and therefore require a large and heavy fan disc to support them.
It is an object of the present invention to provide a fan for a ducted fan gas turbine engine which is lighter than has conventionally been the case.